When upper gastrointestinal cancers (UGC) are combined with colorectal cancer (CRC), mortality from GI cancers is greater than for any other organ system. In 2012, it was estimated that 120,000 men and women were diagnosed with UGC, which caused nearly 90,000 deaths (compared to <50,000 by CRC in the same time period) (see, e.g., Siegel R, et al., 2012. CA Cancer J Clin 2012; 62:10-29). Patients who present with symptoms typically have advanced stage disease; and only a minority, usually early stage patients, is cured (see, e.g., Cleary S P, et al., J Am Coll Surg 2004; 198:722-31; Talsma K, et al., Ann Surg Oncol 2012; 19:2142-8). Remarkably, although the aggregate death toll from UGC exceeds that of CRC, general population screening for UGC does not exist in this country. Tools considered to screen asymptomatic individuals for UGC have been dismissed as too invasive, insensitive, or cost-prohibitive for application at the population-wide level (see, e.g., Gudlaugsdottir S, et al., Eur J Gastroenterol Hepatol 2001; 13:639-45; Inadomi J M, Keio J Med 2009; 58:12-8; Yeh J M, et al., Gastrointest Endosc 2010; 72:33-43; Rulyak S J, et al., Gastrointest Endosc 2003; 57:23-9). A noninvasive, accurate, and affordable screening tool capable of the screen-detection of all GI cancers is needed.